CS 497C - Introduction to UNIX
Lecture 9: The vi/vim Editor
Chin-Chih Chang chang@cs.twsu.edu

Navigation
* You can use the cursor motion keys (arrow keys) to move around the 
  screen. But some terminals don’t recognize these keys.
* vi has its own set of commands that move the cursor: 
 - h - moves cursor left.
 - l - moves cursor right. 
 - k - moves cursor up.
 - j - moves cursor down.
 
Navigation
* You can use the control keys to change the view of displayed text on 
  your window. The four essential scrolling commands are:
 - [Ctrl-f] - Scrolls full page forward.
 - [Ctrl-b] - Scrolls full page backward.
 - [Ctrl-d] - Scrolls half page forward.
 - [Ctrl-u] - Scrolls half page backward.
 - [Ctrl-l] - Redraws the screen.

Navigation
* Precise navigation commands in vi are:
 - b - moves back to beginning of word.
 - e - moves forward to end of word.
 - w - moves forward to beginning of word .
 - 0 or | - moves to beginning of line.
 - $ - moves to end of line.
 - 1G - moves to beginning of file.
 - G - moves to end of file.

Operators
* vi operators are commands for modifying the content of a buffer.
* These are operators to be remembered:
 - d - delete
 - y - yank (copy)
 - p - put back deleted/yanked text
 - c - change
 - ! - filter to act on text 
* These operators perform function in a combination with a command.

Deleting, Moving, and Yanking Text
* These are commands for deleting text:
 - x - deletes character under cursor.
 - X - deletes previous character.
 - d$ or D - deletes from cursor to end of line.
 - dd - deletes current line.
 - dG - deletes till end of file.
 - dw - deletes current word.

Deleting, Moving, and Yanking Text
* These are commands for moving/putting back text:
 - J - joins current line with next line.
 - p - puts deleted/copied text below current line or on right of cursor.
 - P - puts deleted/copied text above current line or on left of cursor.
* These are commands for yanking text:
 - yy or Y - yanks current line.
 - y$ - yanks from cursor to end of line.
 - yw - copies current word.

Changing Text (c and ~) 
* These are commands for changing text:
 - c0 - changes from cursor to beginning of line.
 - c$ or C - changes from cursor to end of line.
 - cw - changes current word.
 - cc - changes current line.
 - cG - changes from cursor to end of file.
 - ~ - reverses case of character under cursor.

Repeating and Undoing Last Editing Instructions 
* To repeat the last command, use . (dot).
* To undo last commands, use:
 - u - undoes last editing instruction.
 - U - undoes all changes made in current line.
 - [Ctrl-r] - redoes previous undo actions (Linux only).